This invention relates to an automated press for semi-automatically installing fasteners, such as clinch nuts end standoffs, in a workpiece. The workpiece may be a sheet metal plate used to fabricate the cabinets or chassis electrical equipment. Normally holes are pre-punched in the sheet where the fasteners are to be inserted. The press has a punch assembly adapted to engage the fasteners and ram the fasteners into the pre-punched holes. The press has a fastener dispensing assembly for delivery of the fasteners to the punch assembly. The punch assembly cooperates with an anvil or die on which the sheet is mounted. The die has a spring-biased alignment pin. The press operator places the sheet so that the spring-biased pin extends through a pre-punched hole. The punch assembly is then activated whereby it captures a fastener. Continuing its insertion stroke, the punch assembly with captured fastener engages the spring-biased pin forcing the pin to a retracted position and the fastener is secured in the hole.
The above describes a prior art automated fastener press. U.S. Pat. No. 3,452,418 provides a more detailed description of a prior art press of this type.
Upon occasion, a fastener may not be properly seated in the workpiece. For example, a fastener may not have been properly fed to the punch assembly and therefore not be present when the punch assembly is activated. Another fault condition occurs when an improper fastener, such as one that is of the wrong length for the particular operation, is fed to the punch assembly. Also the sheet or workpiece may not have been properly positioned causing the fastener to pierce its own hole either partially or entirely. Unless the operator visually notices the fault condition, it would not become apparent until the workpiece was subsequently used for its intended purpose such as assembly as a cabinet for electronic equipment. At that point the workpiece which by then has been formed to its proper configuration may have to be scrapped in its entirety because of the missing, improperly located, or improper hardware. It is quite common for the press operator to fail to detect or notice these fault conditions. The operator is required to conduct a number of repetitive operations in a short period of time and may lose the concentration required to detect a fault. Moreover, the operator may become distracted. A defective workpiece can cause a considerable number of problems as one attempts to complete a more complex assembly with the defective part. The actual loss can be much greater than simply the defective part. Despite a recognition of this problem from the prior art, there has been no adequate solution developed until the present invention.